Magic Turing Machine v5: Rotlung Reanimator / Necroskitter

What does "Turing complete" mean?

There's an idea called "Turing completeness", which is used to indicate that a system has
a particular degree of complexity. Any Turing-complete system is
theoretically able to emulate any other. One way to show that a system
is Turing complete is to make a "Turing machine" in it. This isn't the
only way of demonstrating Turing completeness, but it is one of the more
understandable.
In the discussion on this site I assemble a Universal
Turing Machine from Magic: the Gathering cards.

But doesn't Magic involve the players making lots of choices?

Normally, yes, it does. But occasionally in normal gameplay you get
a sequence of three or four events in a row that are forced to happen
by the cards and the rules of the game. The machine below just extends
this idea to millions of forced choices in a row.

The idea of my Magic Turing machine is that the players do nothing at all, except when the game offers them a choice.

Once the in-game "machine" has started, processing continues without
requiring any choices from the players, with one category of
exceptions: Some of the cards in the machine say "You may [do X]. If
you do, [Y happens]." In these cases, the machine arranges that the
players will be able to do X, in precisely one way. It just requires
the players to always choose to take the game up on any options
they're offered.

(For discussion of the possibility of removing the "may" cards, see the Future Directions page.)

News

20th September 2012: Version 5 Has ArrivedWith all the recent attention from the Internet, it's been brought to my attention again how the (2, 3) universal Turing machine used in versions 1-4 is only a proper universal Turing machine in very specific circumstances, involving an infinitely long nonrepeating section of tape, which the combo failed to deliver. This spurred on my efforts to fix this by making a version instead of the (2, 18) universal Turing machine, and today, the results have gone online. Enjoy.